Circuit device capable of increasing dynamic range of CMOS image sensor and method thereof

The present invention provides a circuit device capable of increasing the dynamic range of a CMOS image sensor and a method thereof. According to the invention, a photo-sensitive pixel circuit is used to output an output signal, in which the photo-sensitive pixel circuit includes a photoelectric diode and a plurality of transistors. A current source is used as a charge replenishment unit to provide electric current replenishment. The electric current is inputted at one end of the photoelectric diode to supply replenished charge to the parasitic capacitance of the photoelectric diode. This can delay the saturation of the photosensitive pixel circuit, thereby increasing the dynamic range of a sensor. Other than this, a feedback circuit can be used and connected to the photosensitive pixel circuit. The feedback circuit receives the output signals of the photosensitive pixel circuit and sends out a control signal based on the output signals in order to control the status of the charge replenishment unit and incre